In the information-oriented society of the 21st century, broadcasting communication services are entering the era of digitization, multi-channel, broadband, and high quality. In particular, as high-quality digital television (TV), portable multimedia player (PMP), and portable broadcasting apparatuses have been increasingly used in recent years, there is an increasing demand for digital broadcasting services that are able to support various receiving methods.
The standard group has prepared various standards to live up to such a demand, and provided various services that can satisfy the needs of users. Accordingly, a method enabling to provide users with better services having excellent performances is necessary.